Flooding method for recovering oil



2 sneet-s'neet 1 L. C. UREN Filed Sept. 17, 192'? FLOODING METHOD FOR RECOVERING OIL Nov. 12, 1929.

LESTER C. UREN Nov. l2, 1929.

L- c. UREN 1,735,481 FLOODING METHOD FOR REOOVERING' OIL Filed Sept. 17. 1927 2 sheets-sheet 2 27a "if 3] 15' tions of electrolytes face wells.

Patented Nov. 12, 1929 UNIT D LESTER C. UREN,

OF BERKELEY, CALIFORNIA, ASSIGNOR TO STANDARD OIL DEVELOP- MENT COMPANYA CORPORATION OF DELAWARE FLOODING METHOD FOR RECOVERING OIL Application med September 17, 1927. Serial No. 220,126.

This invention relates to improvements in flooding methods for the recovery of oil from oil reservoir sands. Such methods, particularly those involving the use of water solu- (sodium carbonate, etc.) have been extensively investigated in recent years. The solution is forced into the oil sand through one or more 'surface wells, displaced oil is collected through other sur- The percentage recovery is necessarily low because the solution reacts with the sand, the oil, or both. The effectiveness of the solution is practically destroyed after it has progressed a relatively short distance from the point of introduction. p

The object of the present invention is to maintain an flicient concentration of oil-displacing agent, or to regenerate or restore it.

In a preferred embodiment of my method, this is accomplished by projecting. a substance facilitating oil-displacement as a crosscurrent at the interface between the oil and the body of liquid expelling the oil from the sand.

In carrying the invention into effect, a mine gallery installation is utilized, for example, of the general type described and claimed in United States Patents 1,634,235 and 1,634,236, granted to Leo Ranney on June 28, 192,7. As described in these patents, a mine shaft is sunk t0 the level of the oil sand and galleries are driven adjacent the sand in the upper or lower cap rock. I-Ioles are drilled from the galleries into the sand, forming mine wells for the collection of oil, introducL tion of oil-expelling media, etc.

The present invention will be fully understood from the following description, read in connection-with the accompanying drawing, in which- Fig. 1 is a diagrammatic perspective view of an inclined block of oil sand, and means for working it by my method;

Fig. 2 is a plan view of the same;

Fig- 3 is a perspective view showing an alternative installation.

v Referring first to Figs. 1 and 2, 1 denotes a mine shaft from which galleries 2, 3, 4 and 5 are driven. These galleries lie in a lower cap rock or foot wall 6, underlying an oil sand 7.

and the able in cases lution through pipe storage tank 11a. The hydrostatic head in deep wells will usually provide enough pressure. The pressure necessary varies widely, depending on conditions in the sand.

Galleries 3 and 4, which run up the dip of the sand, respectively contain pipes 12 and 13, connected at their lower ends with pipes 12a and 13El for supplyin or withdrawing flooding solution. A tan l13b receives depleted solution from pipe 13a. At suitable intervals, for example, every 100 ft. when working a loose sand, mine wells 14 and 15 are formed from the galleries 3 and 4. Nipples 16 and 17 connect the pipes 12 and 13 with these mine wells.

The highest oAup-dip gallery 5 has a series of mine wells 18 dischargingeinto an oil collecting pipe 19, which leads through a pipe 19 to pump 20. This pump forwards the oil through a pipe 21 to a storage tank 21 above ground. Valves 22 are provided on all the mine well nipples, so that the flow of solution and oil maybe controlled as desired. A valve 22a is installed in pipe 10 and a valve 22b in pi e 19. A number of test holes 23 are formed rom the galleries 3 and 4 to tap the oil sand.

A preferred operation is as follows: The oil which will flow naturally from the mine wells is (collected. When the flow of oil diminishes considerably or stops, a solution of sodium hydroxid, sodium carbonate, sodium silicate, or other substance hydrolyzing to produce hydroxyl ions, is forced in through pipe 10, nipples 9, and mine wells 8. An N/ 1() solution is often sufficiently concentrated, but stronger solutions may be desirwhere there is a tendency to rapid depletion. When sodium carbonate is used. as the solution advances itis gradually converted into bicarbonate by ,reaction with tank 13".

lturned toits original eiectiveness.

the sand.

As soon as the concentration of carbonate has fallen to about the minimum effective amount, a fresh solution, preferably concentrated, is injected through a nipple 16 and mine Well 1 4,A preferabl immediatelybelow the plane of contact of tlie iiooding agent and the oil inthe sand. At this time the valve in the correspondingly located nipple 17 is opened, so that some exhausted solution runs out through it and by pipes 13 and 13'3L to Valves controlling influx of solution through mine wells 8 are meanwhile closed. The injection of solution from the side of f,the sand block and Withdrawal from an opposite point on the other side induces a cross-current. The concentrated reagent in this cross-current is taken up b the depleted solution, which is in this Way su stantially reconcentrated solution may be supplied if desired through a pipe (not shown) instead of from'the solution tank 11a. v

The proper point for introducing the restorativaagent may be determined by observing conditions at the test holes 23. These holes may be pluo'ged and opened at intervals for inspection. when the flooding solution reaches thelevel of a test hole, a portion of the solution is collected and analyzed. If depleted, more rea ent is added. P

The distance tween the galleries 3 and 4 should ordinarily be from 300 to 1,000 ft., depending on the permeability of the sand and other conditions. If more than this, the cross-current of restorative agent cannot generally be well established. The gallery 5 may be 300 ft. or more from the gallery 4, the distance being measured along the dip. The method is best applied to the whole productive area of the sand. In some cases, however, portions of `the sand are so protected that they can be worked individually without much loss of the flooding solution to `adjoining portions of the sand. For example, a orous streak of productive sand sometimes ollows a circuitous course both up and down the dip. Such streaks, if Walled in by dense strata, are effectively operated by my method. The advance of the solution through the sand should be as uniform as possible, to avoid pocketing or trapping any of the oil. Substantial uniformity can be obtained by observing the indications at the test holes and regulating valves 22 to diminish or increase the flow of 'solution into the sand and the withdrawal of -oil therefrom. The rate of flow through the sand should be low, say about six to twelve inches a day. At'this rate ample time is given for displacement of th`e oil held both by surface adhesion and capillarity, and to permit equalization of the advancing solution level.

Although only one upper gallery has been A fresh' .and various changes and a advances, expelling the oil before it, the mine wells in each up-dipgallery in turn become the Ejoints for injecting the solution, and the next ,l vals, up to its crest. y As the flooding solution v gher gallery is used for collecting the oil. l In the installation shown in Fig. 3, a pluf rality of pairs of mine galleries 25, 26 and- 27, are driven laterally at increasing depths from a shaft 28 to points adjacent and below an inclined oil sand 29 Connecting branch galleries 25, A26a and 27 are driven parallel to-the strike.y If the structure makes it desirable to do so, the mine galleries may be formed in the cap rock above the sand. Drill holes 30 from the gallery 27 extend upwardly to tap the sand at intervals. The iooding solution is forced through a pipe 31 in the gallery 27 and mine wells 32 in ditional solution or other restorative agent to maintain an effective concentration is injected as required through the drill holes 30 near the interface between oil and solution. Oil is collected through a llnllipesystem 33 in the up-dip gallery 26`and s aft 28. As above vdescribed, each of the up-dipgalleries is first and then for injecting it into the sand, or heat maybe applied to the sand, for example, as described in the patents above mentioned. Instead of adding fresh sodium hydroxid, sodium carbonate or the like, the solution'inthe sand may be regenerated. This may be done in the case of sodium carbonate by withdrawing the lsolution and heating to convert the bicarbonate into carbonate. The regenerated solution may then be returned to the sand, with or without an additional quantity of roil displacing agent.

The installations andmethods described preferred forms, ternative procedures may be adopted within the scope of the appended claims, in which it is my intention to claim all novelty inherent in the invention as broadly as the prior art permits.

I claim: v

1. The improvement in liooding 4methods for recovering oil from an oil-bearing stratum, which are merely illustrative of agent into the stratum, causing the flooding agent to advance through the stratum and adding fresh iiooding agent at a point .in the line of advance remote from the point of origin, whereby the concentration of the advancing fiooding agent is substantially'maincomprises forcing a ilooding f gallery into the stratum to iow therethrough, sand, by injecting concentrated solution from passing an agent for reinforcing the expulone branch gallery, and withdrawing desive action of said medium into the stratum pleted solution from an opposed point 1n the at an angle to the direction of said flow, and :other branch galler withdrawing a portion of said medium from 10. Method according to claim 7, in which 70 a point in opposition to that at which the an electrolyte solution is used, and the inflow l lagent is introduced. of solution is regulated to produce a substan- 3. The improvement in'electrolyte solution tially uniforml advance of solution through flooding methods for recoveringoil from oil the sand.

' sands, which comprises forcin the solution LESTER C. UREN. v75v to flow through the sand, intro ucing concentrated solution in a' direction transverse to such flow in a region wherethe orignal solution has become depleted, and wit drawing thedepleted solution from a point opposite to. that at which the concentrated solution is introduced whereby a cross-current of concentrated solution is formed.

4. Method according to claim 3, inwhich the cross-current is established near the'interfac'1 between the solution and the oil in the san 5. Method according to claim 2, in which the oil-expelling medlum is caused to ow up the ldip ofthe oil-bearingstratum and the reinforcin agent is intro uced through a branch ga lery running up the dip.

6. The improvement in electrolyte solution floodin methods for recovering oil from -an oil san which comprises forcing the solution into the sand from a plurality of closely spaced mine wells to form a body ofy solution advancing through the sand, directing v a streamof fresh solution of a reagent, facilitating displacement of oil, into the sand at a point remote from that at which the body of solution enters .the sand for admxture with the body of solution to maintain an effective concentration therein, and withdrawing oil through .other mine wells.

7. The improvement in recovering oil from an'oil sand, which comprises driving a downdip gallery in the cap rock or foot wall and generall parallel with the strike of the deposit, riving spaced, u wardly-inclined branch galleries from said own-dip gallery, and an up-dip gallery connecting said branch galleries, -formmg mine wells in each gallery, forcing an oil-expelling agent into t e sand from the mine wells in the down-dip gallery, replenishing the agent from the mine we s in the branch galleries, and collectin the oil from the mine wells in the up-dip al ery.

8. `Method according to claim in which an electrolyte solution is used, the condition of the solution, is tested at various points in the branch galleries, and a rea ent facilitating displacement of oil is adde through the mine wells therein, so as to maintain an` effective concentration throughout the progress of the solution througl the sand. y

9. Method according to claim 7, in which an electrolyte solution is used, a 'current of concentrated solution is directed across the 4interface between oil and solution rin the 

